Created attachment 789813 [details] control-center-corners.png Description of problem: Control-center windows are rounded but with square artifacts. See the attachment. I cannot reproduce it with different programs, like gcalctool. Control center seem to be the only one affected. Version-Release number of selected component (if applicable): control-center-3.9.90.1-1.fc20.x86_64 gtk3-3.9.12-1.fc20.x86_64 mesa-dri-drivers-9.2-0.15.20130723.fc20.x86_64 OpenGL renderer string: Mesa DRI Mobile Intel® GM45 Express Chipset
That is a known problem, which should be handled upstream. It affects every app that uses the new GTK HeaderBar. If you start it with GTK_CSD=1 environment variable, you won't see the square "artifacts".
Got fixed somewhere along the way.